Destroyed how? You have to be more specific than that.
By what means, during what time period, etc. Because, eventually everything will be destroyed, including our planet, solar system, galaxy...
Nothing lasts forever. So please, explain your thoughts a little bit more.
I think his idea is that the blockchain system will be attacked and shut down completely. In fact, every system has gaps, certain weaknesses, nothing perfect, we have seen cases of attacks 51%, but to destroy a blockchain system, and make it stop working is very difficult. On the theory of "quantum computers" or "supercomputers" can destroy the blockchain system, but now mankind still can not own it.